A Robotic Exoskeleton Could Teach Stroke Victims How to Walk Again

Tony Stark may be able to fly with his Iron Man suit, but a Harvard professor’s “exosuit” could teach stroke victims how to walk again.

The exosuit is a soft, wearable exoskeleton that fastens around the waist and legs, using cables to gently pull on joints and boost movement. Among several applications, the suit could help stroke victims regain movement quality.

Conor Walsh, a professor at Harvard’s Wyss Institute, originally worked on a rigid exoskeleton as a graduate student at MIT. It was meant to assist people with walking, but the suit’s added mass and the difficulty of matching robotic and natural joints proved problematic. When Walsh started at Harvard and found his team working in soft materials, he became interested in “making wearable robots soft.” Eventually, he and his team developed a smaller, lighter, and more pliable exoskeleton.

Because it’s more difficult to control how much force and assistance a soft exoskeleton provides, the exosuit simply gives a well-timed nudge at the hip or ankle to help users walk more efficiently, and with less effort. It was initially made to improve the gait of healthy people, as well as those who have to bear heavy loads, such as soldiers.

Once Walsh and his team solidified the model, they began thinking of new applications. The question, Walsh says, was “if you can help healthy people walk with a little bit less effort when carrying, say, a heavy load, could you also help restore mobility for someone who can walk, but just not very well?”

Using an exoskeleton to help stroke victims kept coming up. When someone suffers a stroke, Walsh explains, the muscles in one leg are impaired, which makes walking difficult. “Someone who has suffered a stroke walks in a different way than a healthy person would walk,” he says.

Using sensors to detect how the wearer moves and how much force is being used, the suit can determine what stage of walking—lifting a foot, shifting weight, or placing the foot down—the person is in, and adjusts it to match a healthy person’s gait.

“We know from normal human walking what the muscles in the body are doing at those various phases,” Walsh says. “That’s basically how we command motors to try and replicate what a healthy set of muscles would normally be trying to do at that phase of the walking cycle. And we found that to be quite effective so far.”

Although it is already being used in a research capacity at Boston University and Spaulding Rehabilitation Hospital, Walsh hopes that, eventually, the device will work well enough to retrain someone’s gait during physical therapy. The results, hopefully, would stick around even when the suit isn’t on.

Walsh also hopes that by partnering with ReWalk Robotics, a company that makes a rigid, wearable robotic exoskeleton, the exosuit will be approved by the FDA and on the market within a few years. Recently, Walsh and his team were acknowledged by Rolex Awards for Enterprise, which will provide financial assistance.

If you would like to be involved in improving either the medical or load-bearing exoskeleton, please contact clinicalresearch@wyss.harvard.edu to see if you are eligible to participate in research. Medical walkers must have had a diagnosed stroke, and load-bearing walkers must have an occupation that involves bearing weight.